Halogenated polyethylene



Patented Aug. 20, 1946 1 HAIDGENATED roLxEmLENE S Ambrose McAlevy,Kennett Square, Pa., assignor' to E. I. du Pont de Nemours & Company,Wilmington, DeL, a corporation of Delaware hlo Drawing- ApplicationMarch 23, 1943.

. Serial No. 480,211

This invention relates to an improved process for the halogenation of;polymers from organic compounds containing monoolefinic unsaturation,and is more-particularly,related'to an im- Proved process for thechlorination ofpolymers om et e -An object of I an improved process forthe halog'enation of poly mers derivedfrom organic compounds havingmonooleflnic unsaturation and which contain at least one replaceablehydrogen-per structuralunit and molecular weights in excess of 300.Another object is to provide-aprocess tor the chlorination of.monoolefin polymers; which have, molecular weights in excess o f1' 300.to provide an improved process forchlorinating polymers from ethylene,whichhave I molecular weightsinexcess of,--300. ther objectsand'advantages of the invention lwil'l hereinafter appear.

The polymers from ethylene which are halogenated in accord with, thisinvention include the solid to semi-solid i h Q1ccular weight substancesofa polymelic naturewhich are obtained (1) by the. polymerizationtof lethylene alone as described in U. S. Patents 2,153,553 and 2,188,465,(2). by the polymerization of ethylene with other polymerizable organiccompounds as described in U.-S. 2,200,429, (3) bycontacting ethylenealone or in admixture with anotherpolymerizable organic compound withmolecular oxygen, a pcr-oxy,

compound, a hydrazine or hydraziniumcompound or an amine oxide andanormally liquid, substantially inert reaction medium at a temperature intherange of 40f't0 400? C. andat a pressure in excess of atmosphericpreferably in the range of 50 to 3000 atmospheres, or (4 ,by. reactingethylene with a telogen to give, telomers; as described in Jthecopendingapplication Of Hanford 8: Joyce, S. N. 438,466, filedhprllllo, 1942,an'd in the copending application of; Hanford 8: Roland, S. N. 471,028,filed January 1:1943. I e

The polymers of ethylene alone are either semisolid or solidat normaltemperatures, correspond in composition substantially to (CI-12):, andhave molecular weights in excess of 1000. The proper-, ties of thepolymers of ethylene with other polymerizablev organic. compounds varydepending upon the nature oi the polymerizable organic thepresentginventlonis to provide (Still another object is,

f 1 Claim. (01. 2 0-94 oyl peroxide. The amount of catalyst either usedcompound and the composition of the polymer,

The expression polymers from ethylene is used in the description andclaims to reierto the polymers from ethylene alone and also to themodified ethylene polymers, interpolymers and telomers of the abovekind. In accord with this invention the polymers are dissolved orsuspended in an organic solvent, preferably one which is substantiallyinertjand then treated with an oxychloride of carbon or sulfur, in thepresenceof light, with or without the aid of a catalyst, re. 2., aheterocyclic compound containingannular nitrogen. Alternatively, the're-' -.action may be catalyzed by the use, in lieu of light,

of a peroxide catalyst such, for example, as benzwithlight or employedin the alternatereaction can vary from 0.01 to 10% on the weight of theoxychloride, generally the amount which has been found to givesatisfactorily good results is from about 0.10 to 2%.

is then heated, preferably to between 50 and C., with agitation, exposedto a source of actinlc light, and they oxychloride added portion-wise.After completion of the reaction the chlorinated polymer is isolated bymeans well known to the art.

The oxychlorides of carbon or sulfur that may be used include phosgene,(C0012); oxalyl chloride, (C 0Cl)z; sulfuryl chloride, (SOzClz); and,thionyl chloride, SOC12. In general, at least half a mole of theoxychloride is used for each hydrogen to be replaced in the polymer. Asa rule, however, it is advantageous to increase the amount of theoxychloride to one mole.

As a sourceof actinic, light there can be used a high wattage tungstenfilament light, a mercury vapor light, sunlight, carbon arc, ultravioletlamp, infrared lamp, or monochromatic light.

The apparatus may be of glass, enameled vessels, or corrosion resistantalloys.

If desired the process may be carried out as a continuous operation, forexample, by injecting the oxychloride into a hot solution of the polymerflowing through an illuminated tube.

Suitable solvents include carbon tetrachloride, tetrachloroethylene,tetrachloroethane, hexachloroethane, and the like. In place of thesechlorinated aliphatic hydrocarbons there can be used benzene,nitrobenzene, etc. If a low boiling solvent is used it is desirable toconduct the chicrination under pressure for this raises the boilingthereof.

Generally the products obtained from the polymers of ethylene alone arerubbery, flexible, and tough with higher tensile strengths than theoriginal polymers. At 20 to 25% chlorine content the materials aretacky. The tensile strength of the products increases very rapidly withincrease in chlorine content. Above 30% chlorine, the softening pointsreach the range of those of the original polymers. The chlorinatedpolymers from ethylene are in most cases soluble in arcmatichydrocarbons, in chlorinated aliphatic hydrocarbons and in organicesters at ordinary temperatures.

Variation in the chlorine and the sulfur content of the halogenatedpolymer is possible. It has been found that if sulfur dioxide isintroduced throughout the reaction sulfur content of the resultingchlorinated polymer can be increased up to from 5 to It is likewisepossible to augment the chlorine content of the chlorinated polymer byintroducing chlorine throughout the reaction. Furthermore, both gases mabe introduced if an increase in the sulfur and chlorine content overthat obtained by a given concentration of the oxychloride is desired.Variation in the sulfur content of the product is also obtained by theuse of suitable reaction temperatures. In general, the sulfur content ofthe product varies inversely, with reaction temperature over the range10 to 80 C. It is often convenient to lower the reaction temperaturewhen the reaction is only partly complete, for in the intermediateranges of chlorine content (10 to 35%) the resin i sufllciently soluble,in carbon tetrachloride, to permit lowering the temperature withoutprecipitation occurring.

When phosgene is employed as the oxychloride the reaction is partly oneof chlorination, but in runs of 24 hours duration introduction of smallamounts of carbonyl groups into the resin occurs, and an infusible,insoluble product results.

When the product of reaction between an oxychloride and an oleilnepolymeris soluble in the reaction mixture, the. following procedure maybe used for isolating it. y The solvent, excess oxychloride and hydrogenchloride present after the reaction may be removed by simple steamdistillation and the product, subsequently washed and dried on a mill,such as is used in compounding rubber, or contrariwise the productdissolved in benzene, carbon tetrachloride, dichloro difluoroethane,methylene chloride or other suitable solvent is precipitated therefromby an aliphatic alcohol or other liquid miscible with the reactionmedium employed but which is a non-solvent for the chlorinated polytheneproduced.

The following examples illustrate preferred mbodiments of the inventionin which parts are by weight.

Example 1.Twenty-i1ve parts of a polymer of ethylene, having a meltviscosity of 0.1, is dissolved with heating in 500 parts of carbontetra- 4 sulfuryl chloride and 40.5 parts of chlorine are added and themixture heated under reflux, in the light of a 800-watt tungstenfilament, electric lamp, at approximately"l'l C, for 60 minutes. Thereaction mixture is drawn on, drowne in 1500 parts of methanol toprecipitate the chlorinated polymer and after .decantation andfiltration the methanol is removed by treatment with steam. The productanaly es 47% chlorine and 0.56% sulfur.

The melt viscosity herein described is determined by the followingprocedure. An aluminum cylinder of internal diameter open at the top isfitted at the bottom with an 8 mm. steel disk containing at its center a2.1 mm. orifice. The cylinder and disk are heated to a temperature of190 C. and the product to be tested introduced and heated to the sametemperature. Above the surface of the product a piston heated to 190 C.and fl' in diameter is superimposed and upon it a weight i placed givinga combined weight of 2.16 kilograms. The weight of product flowing fromthe orifice in grams per minute is the measure of the melt viscosity.

Example 2.-25 parts of solid ethylenepolymer having a melt viscosity of0.1, is added to 500 parts of carbon tetrachloride and the resultingmixture heated and stirred to effect solution. 57 parts of sulfurylchloride and 0.2 part of benzcyl peroxide are added and the resultingmixture heated under reflux at a temperature of approximately 77 C. forminutes. The carbon tetrachloride, sulfuryl chloride, and hydrochloricacid are steam distilled from the reaction mixture, the reaction productis separated. dried on a rubber mill and is analysed. It contains 30.9%of chlorine with substantially no sulfur.

Example 3.Fifty parts of a polymer of ethylene, having a melt viscosityof 0.1, is dissolved in 1000 parts of carbon tetrachloride and to thesolution there is added 120 grams of sulfuryl chloride. The resultingmixture i heated under reflux and irradiated during the reaction with atype H-4- -watt mercury vapor lamp. After 140 minutes the product issteam distilled, and milled. It contains 34.4% of chlorine.

Example 4.Eight parts ofan ethylene polymer (average molecular weight25,000-30,000) is dissolved in 480 parts of boiling carbontetrachloride, and one-half part of pyridine is added to the solution.As the refluxing solution is stirred and is illuminated, 99 parts ofsulfuryl chloride is added drop-wise over a period of 70 minutes. Themixture is stirred for 2 additional hours. The product precipitates outas a soft tally-like coagulate. The carbon tetrachloride is decantedoil, and occluded solvent, sulfuryl chloride, and hydrogen chloride areremoved from the product by hot-water wash on a rubber mill. The driedproduct is flexible and tough and is soluble at ordinary temperatures inhydrocarbons and organic esters.

It softens at 115 C, to 118 C. and contains 44.1% of chlorine and 2.6%of sulfur.

Example 5.Ten parts of the ethylene polymer described in Example 3 isdissolved in 486 parts of hot tetrachioroethylene, and one-half part ofpyridine is added. As the solution is stirred and is maintained at 100to C., it is exposed to actinic light, and 117 parts of sulfurylchloride is added slowly over a period of 90 minutes. Stirring iscontinued-for 45 additional minutes. No precipitate separates out, andth solution is steam distilled to remove solvent, sulfuryl chloride, andhydrogen chloride. The chlorinated chloride. Into the resulting mixture15 parts of 7s polymer is washed and dried on a mill. It is to removesolvent and impurities.

tough, flexible, and soluble at ordinary temperatures in hydrocarbon andorganic esters. It softens at 115 to 117 C. and contains 53.4% ofchlorine and 0.7% of sulfur. A solvent-cast film 3 mils thick has atensile strength of 4,600 pounds per square inch and an elongation of276% at break. The original ethylene polymer is insoluble in coldsolvents, and a solvent-cast film 4 mils thick has a tensile strength of1,580 pounds per square inch and an elongation of 8% of break.

Example 6.Ten parts of the ethylene polymer of Example 3 is dissolved in405 parts of hot tetrachloroethylene and one-half part of pyridine isadded. During the reaction the solution is illuminated with actiniclight and is stirred vigorously at 100 to 105 C. Fifty parts of sulfurylchloride is added over a period of 80 minutes. The solution issteam-distilled to remove the solvent and impurities. The product iswashed and dried on a rubber mill. It is a soft rubbery material,containing 21% chlorine and only a trace of sulfur, and soluble inhydrocarbons at room temperature and in warm butyl acetate.

. Example 7 .Twenty parts of the ethylene polymer of Example 1 isdissolved in 960 parts of boiling carbon tetrachloride, and 1 part ofpyridine is added. The refluxing solution is illuminated with actiniclight, and 109 parts of sulfuryl chloride is added slowly over a periodof 90 minutes. Stirring is continued for 30 minutes. The coagulatedprecipitate is placed in boiling water After drying in the air overnightthe product is dissolved in methylene chloride and the solution shakenvigorously with powdered sodium bicarbonate to remove last traces ofhydrogen chloride. The sodium bicarbonate is removed by centrifugationand decantation. Clear, colorless, transparent films may be cast fromthe resulting solution. A film 1.! mils thick has a tensile strength of3549 pounds per square inch and an elongation of 308% at break. Theproduct contains 41.4% chlorine and 3% of sulfur.

Example 8.To 5 parts of a liquid propylene polymer having a. molecularweight of 318 is added approximately 0.! part of pyridine, the mixtureis stirred and irradiated with a 500 watt Mazda lamp while adding 5parts of sulfuryl chloride during a period of 15 minutes. Theirradiation is continued for an additional 45 minutes and the reactionmixture is then poured into 500 parts of a 30% aqueous sodium hydroxidesolution. The product is extracted with ether and dried over magnesiumsulfate. The solvent is removed at reduced pressure, and the product isobtained as a yellow liquid. Upon analysis it is B. This analysis showsthat the predominating 65 D n re be ween 50 reaction which occurred waschlorination.

Example 10.-A solution of 15 grams of solid ethylene polymer and 3 gramsbenzoyl peroxide in 300 cc. benzene is kept saturated with phos= gene ata temperature close to the'boiling point of the solvent. This mixture isirradiated with a 300 watt tungsten filament lamp for 24 hours. Theresulting resin. is somewhat similar to the ethylene polymer inappearance, but is infusible and insoluble.

In place of the polymer set forth in the above examples there can beused any polymer derived from an organic compound containingmonoolefinic unsaturation and which contains at least one replaceablehydrogen per structural unit, said polymer being further characterizedby having a molecular weight of at least 300. Specific examples ofpolymers which can be used in the practice of this invention includevinyl acetate, polyvinyl chloride, polystyrene, polymethylacrylate,polymethyl methacrylate, etc., the polymers of vinyl chloride witheither vinyl acetate, fumaric esters, maleic esters, or vinylidenechloride; the

polymers of ethylene with amylene, styrene, stilbene, vinyl acetate,methacrylic esters, ethyl itaconate, diethyl citraconate, diethylmaleate, di=

ethyl fumarate, acrylic esters, vinyl chloride, vinyl fluoride,chlorotrifluoroethylene, vinylidene fluoride, vinylidene chloride,tetrafiuoroethylene, maleic anhydride, vinyl butyl ether, eta; polymersof vinylidene chloride with acrylonitrile, methacrylic esters,tetrafiuoroethylene, vinyl chloride, etc., and methyl methacrylate,styrene, or vinylidene chloride.

The products may be removed from the reac-- tion mixture and purified bymeans already described or the reaction mixture may be injected at thebottom of a vessel containing boiling water, whereupon the solvent andimpurities will flash off or dissolve and the purified polymer may beskimmed off the top of the water. If the product is still in solution itmay be precipitated from solution with alcohol or any liquid misciblewith the solvent but not itself a solvent for the polymer. The polymermay then be redissolved in a suitable solvent and similarlyreprecipitated any desired number of times. Drying may be' carried outin the air or in a vacuum oven at a slightly elevated temperature.

The chlorinated products are applicable for use in wrapping films, incoating and waterproofing fabrics, as protective liners for acid or basecontainers, in lacquers for wood, cement, or metal,

as gaskets and washers, etc.

I claim: 1

A process of chlorinating a polymer from ethylene having a molecularweight of at least 300 obtained by polymerizing ethylene at atemperature between 40 and 400 C. under pressures between 350 and 3000atmospheres and in the presence of a catalyst selected from the groupconsisting of oxygen and peroxy compounds which comprises reacting thesaid polymer in solution in carbon tetrachloride with sulfuryl chloridein the presence of benzoyl peroxide and at a temand C. 1

AMBROSE McALEVY.

